As described in U.S. Pat. No. 4,317,994 (Mallozzi, et al., Mar. 2, 1982), the development of laser-plasmas as an X-ray source for EXAFS has made possible a wide variety of significant experiments that were previously impossible or impractical. However, many of these experiments involve organometallic compounds in which the component of interest is in very low concentration, i.e., iron in blood or magnesium in chlorophyll. In addition, studies on may organic compounds with low concentrations of phosphorus, sulfur, chlorine, potassium, and calcium are of interest. One problem with these low concentration experiments is the poor spectral resolution due to the low signal to background noise ratio. Another difficulty with EXAFS experiments is the necessity for preparing very smooth and very thin samples. These sample requirements often rule out the EXAFS technique for routine laboratory or industrial applications.
Both of these problems can be overcome by using a fluorescence X-ray detection system. Such a detection system has been estimated to enable EXAFS experiments on samples as dilute as 0.01 ppm (Sparks, C. J., "Research with X-rays" Physics Today, 1981, 34(5), pp. 40-47.). This detection system also allows for the use of a wide variety of sample states such as solids, powders, and liquids and obviates the need to prepare the very smooth and thin samples required with conventional EXAFS techniques. As a result, this technique is much more amenable to routine laboratory and industrial applications.